In 2015, she confessed to an Australian magazine that she lied about the diagnosis. It also emerged that she failed to make donations she had publicly pledged to charity.

"If there is one theme or pattern which emerges through her conduct, it is her relentless obsession with herself and what best serves her interests," Justice Debra Mortimer said in handing down the fine for misleading and deceptive conduct.

35-year-old Gibson, who did not attend the hearing, made some Aus$420,000 from her book and a popular social media business, promising much of the earnings to charity.

Mortimer said people bought her app as they incorrectly believed profits were going to a good cause.

In one of "the most serious" instances Gibson promised a week's earnings to a family whose child had a brain tumour.

"She did this to encourage members of the public to buy her product (The Whole Pantry app), to generate income for herself and her company, and generally to promote herself and her commercial activities," the judge said.